In the last 100 years the concentration of CO2 in the atmosphere has increased from about 300 ppm (parts per million) to over 360 ppm today. Most people agree that the burning of fossil fuels has caused this increase and that the increased CO2 may result in a warming of the earth due to the "greenhouse effect". (CO2 absorbs light energy and releases heat which is trapped by the atmosphere.) What effect these potential changes will have on plants, however, is harder to predict.

Questions: 1. Since CO2 is a substrate for Rubisco, and this enzyme is not saturated by current atmospheric concentrations of CO2 (due to its high Km for CO2), what effect will increased CO2 have on photosynthesis? 2. If the average temperature on earth increases, what effect will this have on plant metabolism? Consider that with increasing temperatures the rate of water loss by leaves will also increase. 3. Lastly, increasing temperatures and changing rainfall patterns may cause dramatic shifts in climate necessitating that plants migrate or evolve new adaptations. What might happen if the climate changes faster than the rate of plant migration or adaptation?

8/22/04 Copyright (C) 2004, Jonathan Monroe, monroejd@jmu.edu. All rights reserved.
URL: http://csm.jmu.edu/biology/courses/bio220/qotw5.html